Gating is a strategy for correcting cardiac and respiratory patient motion which occurs during medical imaging. Gating works by subjugating raw data into separate bins, which correlate with separate segments of the motion cycle. By applying such traditional gating techniques, systems are able to achieved improved resolution, but at the cost of image statistics.
Several methods have been proposed for sorting gated data in an “optimal” way. Because patient motion characterization traditionally comes in an amplitude vs time format, usually from a hardware based device, most strategies to date have either sorted raw data by amplitude, or time. More specifically, data is subjugated into gated data by separating it by its associated amplitude, or the phase (time between cycles) it was acquired at.
Both amplitude and phase based gating strategies have advantages and disadvantages. Amplitude-based strategies can be used to optimally segregate data, but they also suffer from drifting of hardware (changing baseline), are subject to instrument noise, and are less ideal to use with data driven motion characterization strategies. Phase-based gating can be more robust, and has advantages associated with equal segregation of statistics.